Fix rest validation of search request using a PIT (elastic#71688)

The rest validation of the search request ensures that the indices options
are set to the default value. However, the comparison is too strict and should
use equals since we create a new IndicesOption object when parsing from http or transport.

Closes elastic#69974

Author: jimczi

server/src/main/java/org/elasticsearch/action/search/MultiSearchRequest.java

@@ -315,7 +315,7 @@ public static void writeSearchRequestParams(SearchRequest request, XContentBuild
         if (request.indices() != null) {
             xContentBuilder.field("index", request.indices());
         }
-        if (request.indicesOptions() != null && request.indicesOptions() != SearchRequest.DEFAULT_INDICES_OPTIONS) {
+        if (request.indicesOptions().equals(SearchRequest.DEFAULT_INDICES_OPTIONS) == false) {
             WildcardStates.toXContent(request.indicesOptions().getExpandWildcards(), xContentBuilder);
             xContentBuilder.field("ignore_unavailable", request.indicesOptions().ignoreUnavailable());
             xContentBuilder.field("allow_no_indices", request.indicesOptions().allowNoIndices());

server/src/main/java/org/elasticsearch/action/search/MultiSearchRequestBuilder.java

@@ -44,8 +44,8 @@ && request().indicesOptions() != IndicesOptions.strictExpandOpenAndForbidClosed(
      * same order as the search requests.
      */
     public MultiSearchRequestBuilder add(SearchRequestBuilder request) {
-        if (request.request().indicesOptions() == SearchRequest.DEFAULT_INDICES_OPTIONS
-            && request().indicesOptions() != SearchRequest.DEFAULT_INDICES_OPTIONS) {
+        if (request.request().indicesOptions().equals(SearchRequest.DEFAULT_INDICES_OPTIONS)
+                && request().indicesOptions().equals(SearchRequest.DEFAULT_INDICES_OPTIONS) == false) {
             request.request().indicesOptions(request().indicesOptions());
         }
 

server/src/main/java/org/elasticsearch/rest/action/search/RestSearchAction.java

@@ -48,6 +48,7 @@
 import static java.util.Arrays.asList;
 import static java.util.Collections.unmodifiableList;
 import static org.elasticsearch.action.ValidateActions.addValidationError;
+import static org.elasticsearch.action.search.SearchRequest.DEFAULT_INDICES_OPTIONS;
 import static org.elasticsearch.common.unit.TimeValue.parseTimeValue;
 import static org.elasticsearch.rest.RestRequest.Method.GET;
 import static org.elasticsearch.rest.RestRequest.Method.POST;
@@ -316,7 +317,7 @@ static void preparePointInTime(SearchRequest request, RestRequest restRequest, N
         if (request.indices().length > 0) {
             validationException = addValidationError("[indices] cannot be used with point in time", validationException);
         }
-        if (request.indicesOptions() != SearchRequest.DEFAULT_INDICES_OPTIONS) {
+        if (request.indicesOptions().equals(DEFAULT_INDICES_OPTIONS) == false) {
             validationException = addValidationError("[indicesOptions] cannot be used with point in time", validationException);
         }
         if (request.routing() != null) {